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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
two-generation reproductive toxicity
Remarks:
based on test type (migrated information)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Comparable to a guideline study. Rationale for using a read across substance is included in overall remarks section.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1984
Report Date:
1984
Reference Type:
publication
Title:
Reproductive effects of diethylene glycol and diethylene glycol monoethyl ether in Swiss CD-1 mice assessed by a continuous breeding protocol
Author:
Williams J et al
Year:
1990
Bibliographic source:
Fundament Appl Toxicol 14, 622-625

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: NTP Fertility assessment by continuous breeding
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Deviations:
yes
Remarks:
P generation no organ weights, sperm parameters or oestrous cycle included; P animals slightly older than recommended at first exposure;
GLP compliance:
no
Remarks:
but full quality control auditing procedure used.
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
The test material was confirmed to be > 99% pure.

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
Animals were 6 weeks old upon receipt and were quarantined for 2 weeks. During this period, 2 females and 2 males were killed and their serum was analyzed for 11 viruses. All tests were negative.
Mice were allowed free access to food and water.
They were randomly assigned to groups by body weight.
Eleven-week old mice were allocated into 4 treatment groups.

Administration / exposure

Route of administration:
oral: drinking water
Vehicle:
water
Details on exposure:
no additional data
Details on mating procedure:
Parental: During premating exposure sexes housed separately (5/cage), females and males from the same dose group were then paired, housed one breeding pair per cage, and cohabitated for 98 days. The pairs were separated and the male and female mice were housed individually and exposed for an additional 3 weeks.
F1: After weaning F1 animals were continuously treated, and paired with nonsiblings from the same dose group at 74 +/- 10 days. These animals were cohabitated either for 1 week or until a copulatory plug was detected.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Stock solutions of test material were analyzed for concentration at approximately 6-week intervals. They were found to be within 99-104% of target levels.
Duration of treatment / exposure:
premating exposure period: 1 week
mating exposure: 14 weeks
postmating exposure: 3 weeks
Total exposure: 126 days
Frequency of treatment:
continuous
Details on study schedule:
- F1 parental animals not mated until 74+/-10 days after selected from the F1 litters.
- Selection of parents from F1 generation when pups were 21 days of age.
- Age at mating of the mated animals in the study: 9-12 weeks
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 0.25, 1.25, and 2.5% w/v
Basis:
nominal in water
No. of animals per sex per dose:
40/sex for untreated controls and 20/sex in each of the following dose groups: 0.25, 1.25, and 2.5% w/v.
Control animals:
yes, concurrent vehicle
Details on study design:
An initial dose finding study was performed in which 8 animals/sex were exposed to 0, 1, 2, 3, 4 and 5% in the drinking water for 14 days. Doses chosen for use in the reproductive toxicity study were a dose that produced no effects, a dose that produced minimal toxicity, and a high dose that reduced body weight by approximately 10%.
Positive control:
none

Examinations

Parental animals: Observations and examinations:
Water consumption, parental body weights (time was not specified), mortality and clinical signs of toxicity of parents were evaluated.
Oestrous cyclicity (parental animals):
not examined
Sperm parameters (parental animals):
not examined
Litter observations:
The day of delivery of each litter, the number of litters per breeding pair, the number and percentage of fertile pairs, the number, percentage and sex of live pups per litter, and the mean body weights of live offspring were recorded.
Postmortem examinations (parental animals):
Because reproductive effects were not observed during the 126-day exposure period, the F0 parents were not necropsied.
Postmortem examinations (offspring):
The fifth or final litters from mice treated with 0% or 2.5% DEGEE were reared and weaned at Day 21 (all others were euthanized).
The F1 parents were euthanized and necropsied. Body, liver, brain and pituitary weights were recorded. Selected reproductive tissues from males (left testis with epididymis attached, right testis, right epididymis, prostate and seminal vesicles) and females (ovary with oviduct attached, and uterus) were weighed, fixed and embedded in paraffin, stained and evaluated by light microscopy. The sperm concentration, percentage of motile sperm, and percentage of abnormal sperm in the right cauda epididymis also were evaluated.
Statistics:

The Cochran-Armitage test was used to evaluate any dose-related trends in fertility. The cumulative days between litters were assessed by William's test. Pairwise comparisons were made using Fisher's exact test. A
Kruskal-Wallis analysis of variance on ranks was used to compare the number of litters per breeding pair and the number and sex of live pups among treatment groups. The Wilcoxon-Mann-Whitney U test was used to make intergroup pairwise comparisons. Ordered differences were tested for by Jonckheere's test. An analysis of covariance was performed to correct for the potential effect of the number of pups per litter on the average pup weight. Average organ weights adjusted for body weight were tested for equality by the covariance method used for pup body weights. Absolute organ weights were analyzed by the Kruskal-Wallis and Wilcoxon-Mann-Whitney U tests.
Analyses were performed on data for males and females separately and with both sexes combined. Pairs in which one or both partners died were excluded from the analysis. The criterion for significance was p < 0.05.
Reproductive indices:
Fertility Index (%) =( No. Fertile/No. cohabited )x100
Mating Index (%) = (No. with copulatory plugs/No. cohabited) x 100
Offspring viability indices:
proportion of pups born alive

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Mortality:
mortality observed, non-treatment-related
Description (incidence):
A total of 6 F0 animals died; one control male and female, one female in the 0.25 and 1.25% groups and two males in the high dose group.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
There were small decreases in the mean body weights of high dose males during weeks 1 and 5, which amounted to a 6% decrease compared to control.
Food consumption and compound intake (if feeding study):
no effects observed
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Daily water consumption was monitored. During the first week, there was a significant (albeit slight) decrease in water consumption in high dose F0 males. However, at Week 13, the pairs given the high dose consumed more water than controls.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Description (incidence and severity):
Examined in F1 generation.
Reproductive performance:
no effects observed
Description (incidence and severity):
Fertility index 100% at all doses

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
ca. 1.25 other: % in diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
water consumption and compound intake

Target system / organ toxicity (P0)

Critical effects observed:
no

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
mortality observed, non-treatment-related
Description (incidence and severity):
one female at 2.5% died during week 4.
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
There was a 3% reduction in adjusted live pup weight for males from the 0.25% dose group, and a 5% reduction in this parameter for females in the high dose group. The effects on pup weights were considered by the investigators to have questionable biological significance since they were not dose-related in males and were small in females.
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
effects observed, treatment-related
Description (incidence and severity):
Sperm analyses on F1 males demonstrated a significant decrease (34%) in the percentage of motile sperm from the cauda epididymis of high dose males compared to controls. There was no effect on fertility or reproduction of the F1 generation mice despite this effect on sperm. Fertility index: 100% (at 0%) and 84% (at 2.5%).
See table in remarks.
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
The only significant changes observed in high dose F1 animals at necropsy were decreases in the absolute and relative brain weights of both sexes, and an increase in the absolute and relative liver weights of females and relative liver weight of males.
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed
Description (incidence and severity):
No histopathological changes were seen in any of the organs that were examined (including the testes).
Other effects:
no effects observed
Description (incidence and severity):
VIABILITY (OFFSPRING)
0.99+/-0.01, 0.97+/-, 0.98+/-, and 0.99+-/0.00, for 0, 0.25, 1.25 and 2.5% respectively.

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
ca. 1.25 other: % in diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Sperm motility only

Target system / organ toxicity (F1)

Critical effects observed:
not specified
Lowest effective dose / conc.:
2.5 other: % in diet
System:
male reproductive system
Organ:
other: testes (not specified) - sperm motility
Treatment related:
not specified
Dose response relationship:
not specified
Relevant for humans:
not specified

Results: F2 generation

General toxicity (F2)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings:
not specified

Developmental neurotoxicity (F2)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F2)

Developmental immunotoxicity:
not examined

Effect levels (F2)

Dose descriptor:
NOAEL
Generation:
F2
Effect level:
ca. 2.5 other: % in diet
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects

Target system / organ toxicity (F2)

Critical effects observed:
no

Overall reproductive toxicity

Reproductive effects observed:
no
Relevant for humans:
yes

Any other information on results incl. tables

Assuming an average daily water consumption of 7 ml per 40-g mouse, drinking water concentrations of 0.25, 1.25 and 2.5% diethylene glycol monoethyl ether (DEGEE) represented average daily intakes of approximately 440, 2200 and 4400 mg DEGEE/kg/day, respectively.

Analyses pertaining to reproduction of F1 control and high dose males are listed in the following table. Corresponding data for F0 animals were not available. Values are presented as mean +/- SEM.

Parameter                             

Treatment

(% DEGEE)

 

0

2.5

Body weight (g)                   

34.7 +/- 0.7

34.2 +/- 1.1

Left testis/epididymis wt (mg)

174 +/- 7

172 +/- 6

Right testis wt (mg)               

123+/-6

123+-6

Right epididymis wt (mg)

50 +/-1

49+/-2

Prostate wt (mg)

35+/-4

37+/-4

Seminal vesicle wt (mg)

329+/-18

350+/-16

Percentage motile sperm

64+/-5

42+/-6*

Sperm concentration (no. sperm x10E3/mg caudal epididymis)

627+/-47

614+/-42

Percentage abnormal sperm (excluding tailless)

2.3+/-0.3

3.5+/-0.7

* significantly different from 0% group at p<0.05

F0 animals were not necropsied. Therefore, sperm parameters, histology and gonad weights of these animals were not assessed.


Applicant's summary and conclusion

Conclusions:
Under the conditions of this reproductive study the test substance at doses as high as 2.5% (2200mg/kg/day) in the drinking water was not a reproductive toxicant deispite a decrease in sperm motility.
Executive summary:

In a two-generational study investigated the effects in reproduction and fertility of 0%, 0.25%, 1.25%, and 2.5% 2 -(2 -ethoxyethoxy)ethanol in drinking water. Male and female CD-1 mice were continuously treated for 1 week prior to mating and for a 14 week breeding period followed by a 21 day holding period when they were separated and housed individually. There were two deaths among the male F0 animals treated at high dose and small decreases in the mean body weights. The body weights of the F1 offspring exposed to 2.5% level were slightly depressed at birth, at weaning and at 74 +/-10 days. 2 -(2 -ethoxyethoxy)ethanol did not have adverse effects on fertility and reproductive performance despite a 34% decrease in caudal epididymal sperm motility in the F1 males at 2.5%. The highest dose also increased liver weight and decreased brain weight in both sexes of the F1 generation. The NOAEL for F0 and F1 generations can be established at 1.25% 2 -(2 -ethoxyethoxy)ethanol based on systemic and reproductive (sperm motility) effects respectively (equivalent to 2200mg/kg), and 2.5% for the F2 generation.

The substance 2 -(2 -ethoxyethoxy)ethanol is a very close analogue of the test substance used in the study and this result can be considered highly predictive of the toxicity of 2 -(2 -methoxyethoxy)ethanol.